In subsea connectors one of the critical regions is the termination of the subsea cable to the connector in a cable gland. To ensure a reliable connection to the cable, it is important that the cable is held in place correctly and with minimal electrical resistance. Furthermore it is important that any external pulling or twisting forces acting on the cable cannot cause the cable to move, or to be pulled out of the gland.
Difficulties with clamping the cable result from the general construction of the cables. Cables often comprise a metallic core, typically copper, with several layers of rubber, plastic and metal to form the cable insulation, earth screen and protective outer jacket. The metallic core must be fitted to the connector in the cable gland such that there is both an effective electrical connection to allow proper operation of the cable and an effective mechanical connection to prevent the cable parting from the connector. For controls and instrumentation type connectors, this typically involves soldering the cable core to the connector, meaning that manufacturing the connections is a skilled and time consuming operation. Soldered joints are difficult to make within the confines of the backends of control connectors because the interface is densely packed and deeply recessed. Cables add obstruction and clutter and joint making requires considerable operator skill to attain quality and repeatability. It is also desirable that the joint produced can be recycled and achieving this is another highly skilled task. Furthermore, there are health and safety concerns associated with manufacturing soldered joints and problems with contamination due to the flux removal process. One option to avoid soldering is to use a crimp type cable joint.
U.S. Pat. No. 7,311,565 addresses the desire for a cable connection system which has good electrical and mechanical properties by providing a viewing window to enable a check to be made that the cable connector has been inserted sufficiently far, as well as a marker recess located on the body of a clamping cone away from the cable, so that a clamping sleeve can be screwed up to the correct extent.